Calculating the $$\rho$$ radiative decay width with lattice QCD

Conference · Wed May 29 04:00:00 EDT 2019

DOI:https://doi.org/10.22323/1.334.0065· OSTI ID:1983870

Leskovec, Luka; Alexandrou, Constantia; Negele, John; Meinel, Stefan; Paul, Srijit; Petschlies, Marcus; Pochinsky, Andrew; Rendon, Gumaro; Syritsyn, Sergey

We present the results of our lattice QCD study of the $$\pi\gamma\to\pi\pi$$ process, where the $$\rho$$ resonance appears as an enhancement in the transition amplitude. We use $$N_f=2+1$$ clover fermions on a lattice of $L=3.6$ fm and a pion mass of $320$ MeV. Using a combination of forward, stochastic, and sequential propagators, we calculate the two-point and three-point functions that allow us to determine the $$\pi\gamma\to\pi\pi$$ matrix elements for several values of the invariant mass $$s$$ and momentum transfer $q^2$. To fit the $q^2$ and $$s$$ dependence of the $$\pi\gamma\to\pi\pi$$ amplitude, we explore a set of general parametrizations based on a Taylor expansion. By analytic continuation to the complex pole corresponding to the $$\rho$$ resonance, we determine the resonant form factors and calculate the radiative decay width of the $$\rho$$.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1983870
• Report Number(s): JLAB-THY-18-2874; DOE/OR/23177-6312
• Country of Publication: United States
• Language: English